A lithography technique which leads development of micropatterning of a semiconductor device is a very important and an only process which generates a pattern in semiconductor manufacturing processes. In recent years, with a high degree of integration of an LSI, a line width of circuit required for a semiconductor device is gradually miniaturized every year. In order to form a descried circuit pattern on the semiconductor device, a high-precision master pattern plate (also called a reticle or a mask) is necessary. An electron beam pattern writing technique using an electron beam (included in charged beams) has an essentially excellent resolution. For this reason, the electron beam pattern writing technique is used in production of a high-precision master pattern plate or a mask.
Prior to pattern writing of an electron beam photolithography apparatus, a layout of a semiconductor integrated circuit serving as a base of a pattern to be written is designed, and layout data (design data) is generated. The layout data is converted to generate internal control format data for the electron beam photolithography apparatus. Furthermore, in the pattern writing circuit, the internal control format data is divided into shot data of a format of the electron beam photolithography apparatus. The shot data is written on a target object on the basis of predetermined writing conditions.
FIG. 7 is a conceptual diagram for explaining an operation of a conventional variable-shaped electron beam photolithography apparatus. An opening 702 having a rectangular shape, for example, an oblong shape to shape an electron beam is formed in a first aperture plate 700 in the variable-shaped electron beam photolithography apparatus (EB photolithography apparatus). In a second aperture plate 704 formed is, for example, an arrow-shaped variable-shaped opening 706 to shape the electron beam having passed through the opening 702 of the first aperture plate into a desired rectangular or triangular shape.
An electron beam 710 emitted from a charged particle source 708 and having passed through the opening 702 of the first aperture plate is deflected by a deflector (not shown). The deflected electron beam 710 passes through a part of the variable-shaped opening 706 of the second aperture plate 704 to irradiate the electron beam on a target object 712 placed on a stage which continuously moves in a predetermined direction (for example, an X direction).
More specifically, a rectangular shape corresponding to an electron beam which can pass through both the opening 702 of the first aperture plate 700 and the variable-shaping opening 706 of the second aperture plate 704 is written in a pattern writing region of the target object 712 placed on a stage which continuously moves in the X direction. A method which causes the electron beam to pass through both the opening 702 of the first aperture plate 700 and the variable-shaping opening 706 of the second aperture plate 704 to form a variable shape is called a variable-shaped beam method.
In such a method using a variable-shaped beam, the number of times of exposure or shot can be made smaller than that in a method using a fixed size spot beam. For this reason, a throughput advantageously increases. As a technique which increasing a throughput, a stage continuously moving scheme is also proposed. This technique is a scheme which performs pattern writing without stopping a stage having a target object placed thereon. According to this scheme, stepping or moving time for a conventional step & repeat scheme which stops the stage during pattern writing can be reduced.
Furthermore, a so-called vector scanning scheme is also proposed which divides a region to write into small regions called sub-fields and deflects and irradiates a variable-shaped beam on only a portion on which a pattern must be written. On the other hand, a conventional one-dimensional scanning scheme scans all writing region with beam off for no-pattern area. For this reason, an increase in throughput can be achieved after all (see Published Unexamined Japanese Patent Application No. 10-284392, for example).